Kitasamycin (INN) is a macrolide antibiotic. It is produced by Streptomyces kitasatoensis. The drug has antimicrobial activity against a wide spectrum of pathogens. Kitasamycin Tartrate In 1953, HATA, et al. reported the isolation of a new antibiotic complex known as kitasamycin (leucomycin). The organism producing this antibiotic complex was obtained from soil samples and named Streptotnyces kitasatoensis HATA. In 1967, eight components were separated and their chemical structures determined. This antibiotic was approved by Ministry of Agriculture in 2001 as the growth promoter additive in poultry and swine to control and prevent digestive and respiratory diseases. Belonging to the macrolide antibiotic, its antibacterial activity is similar to tylosin, erythromycin, spiramycin and oleandomycin. The mode of action is to inhibit the protein synthesis process. Its inhibition spectrum includes Mycoplasmas, Gram-positive bacteria, some Gram-negative bacteria, Leptospira, Rickettsia. It also inhibits most bacteria resistant to penicillin, oxytetracycline, chlortetracycline, erythromycin and chloramphenicol bacteria strains. It is a safe and high efficacy growth-promoting additive for swine and poultry. Although this antibiotic was evaluated many years ago, it was felt of interest to determine its activity against recent isolates of gram-positive cocci. Consequently, the in vitro activity of kitasamycin was determined against 214 gram-positive cocci isolated from clinical specimens. Kitasamycin has activity against the vast majority of clinical isolates of S. aureus, Str. pyogenes and Dipl. pneumoniae, but in vitro studies do not suggest that it has any advantages over currently available antibiotics, although it would be expected to be effective in clinical situations in which erythromycin is indicated.